There's no doubt that Russia's occupation in Crimea represents the biggest foreign policy challenge to date for US President Barack Obama. After his hesitating course with Iran and in the Syria conflict, many in the United States are questioning his abilities as a crisis manager. "Is Mr. Obama tough enough to take on the former KGB colonel in the Kremlin?," asked journalist Peter Baker provocatively this week in "The New York Times."

The US president is facing no shortage of pointed criticism at the moment. Ex-campaign rival Senator John McCain has called Obama's foreign policy "feckless," saying it's partly responsible for the current crisis in Ukraine. In a recent DW interview, he accused the Obama administration of having no strategy at all when it comes to security policy.

Many associate the president with the approach of "leading from behind." Quandaries over Iran and Syria dented his foreign policy reputation, and it was Russian President Vladimir Putin who seemed to take the lead on the affair surrounding whistleblower Edward Snowden.

A 'democratic noose' for Russia?

But Lee Andrew Feinstein, the former US ambassador to Poland, defended Obama's leadership on the latest crisis in Ukraine: "I think, to be fair, President Obama and Secretary Kerry have responded very strongly to these Russian provocations. The secretary of state has called this international aggression. President Obama has called it a clear violation of international law."

It was only days later, Feinstein added, that Europe spoke out with similarly strong language - citing that as an instance of "American leadership." The diplomat said it's now essential that Putin be left an "off-ramp" so that he can change his course without losing face.

Not all of those giving Obama advice favor the latter approach. Republican Senator Lindsey Graham, for example, recommended putting "a democratic noose around Putin's Russia." His Florida colleague and potential Republican presidential candidate, Senator Marco Rubio, wants to "revisit the missile defense shield" - without mentioning that this system has already begun to be installed. Others want to throw Putin out of the Group of Eight.

Limited room to maneuver

Just after Russia began sending units to Crimea, the former US ambassador to Germany, John Kornblum, emphasized the US had limited leverage in an interview with DW. It's a question of defending territorial integrity, he said, adding, "But then if you say that, what does that mean? Obviously, it doesn't mean military action, but it could mean strong political action, and if necessary, economic action."

Obama was quick to tell Putin there would be a cost to sending troops to Crimea. His administration is currently preparing a package of economic sanctions, and Obama supports internationally isolating Russia. Putting an end to preparations for a G8 summit in Sochi was a first step in this direction. US Secretary of State John Kerry said in Kyiv that the goal is to isolate Russia politically, diplomatically and economically. At the same time, he provided Ukraine a pledge for $1 billion in loan guarantees for the country's faltering economy.

As such, the sketch of Obama's plan is now clear: put economic and diplomatic pressure on Russia, while simultaneously offering support to Ukraine's new government. There are no major calls for military action in the US at the moment.

Should the situation further escalate such that Russia seeks official annexation of Crimea, Feinstein said the US would react by freezing Russian assets and limiting Russian businesses' access to international financial markets. That would be a significant move, according to Feinsten.

"Remember: This is not the Russia of 1980 at the time of the Soviet invasion of Afghanistan," he said. "This is Russia integrated into the world economy in 2014."

Solidarity with Europe important

There's good reason for Obama to seek collaboration with Germany and the EU on Ukraine. Without Europe, the American economic sanctions would be useless because Europe's trade volume with Russia is about 10 times higher than that of the US. As a result, European leaders are being guarded with their words.

If Putin cannot be brought to change course or even sends his troops into Ukraine's eastern provinces, the result, warns Feinstein, would be "a long-term, systematic, broad-gauged policy of economic pressure and diplomatic isolation that would be intended to last for a long period of time."

Bush and Obama

Similar rhetoric was used in 2008 when Russian troops occupied parts of Georgia - positions that Russia still has not vacated. George W. Bush was president at the time, and the media also zeroed in on the same - limited - options available to him that are now available to Obama.

"It's popular at this time to talk about the limitations of what the United States and Europe can do," Feinstein said. "But if the United States and Europe are united and speaking with one voice, there's a lot that our countries can do together."

Further, he added that Putin is not at the head of an island: "Russia has got plenty of its own resources and money - and energy, of course - but it also is very deeply integrated into the international economy. And I wouldn't underestimate the impact on Putin."

Although de-escalation and diplomacy are in the foreground for the US and EU's current strategies, there are hints that the West isn't prepared to dismiss the option of military force entirely. When it comes to "other possible areas of cooperation," Feinstein said it's still too soon to discuss them seriously. But despite Ukraine not being a member, he noted that NATO is making plans, saying, "NATO is a mutual defense organization. And let's hope we don't have to go down that road."